diff --git a/doc/advanced_usage.md b/doc/advanced_usage.md
index 53b4fbf..d768151 100644
--- a/doc/advanced_usage.md
+++ b/doc/advanced_usage.md
@@ -302,6 +302,7 @@ Column  | Content
 
 #### variables `evtSyn` and `evtSynSpec`
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+In `eventList`, when the 4th column (event type) equals 4 or 10 (add or cut synchronous generators, respectively), the index of the synchronous generator events in `evtSyn` corresponds to the 5th column of `eventList`. 
 ##### variable `evtSyn`
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